1. Field of the Invention
The present invention relates to mobile communication systems, and more particularly to a system and method of managing the location and/or movement of mobile IP terminals within a mobile communication system.
2. Background of the Related Art
Mobile IP (Internet Protocol) is a wireless network in which data from one mobile terminal is transmitted/received from a second terminal over a signal path which includes the Internet. Mobility management refers to the process of tracking the location of a mobile IP terminal within a service area. Mobility management is hard to perform on the Internet since the Internet is a distributed system, i.e., depends on the distributed nature of networks and location information is distributed around Internet.
In contrast, the mobility management of cellular networks is easier to perform than on the Internet because cellular networks are centralized systems. In cellular networks, mobility management is performed using two schemes: location updates and paging. On the other hand, conventional Mobile IP uses registration only. This produces further differences. For example, in conventional mobile IP, registration is performed in a manner different from location updates on cellular networks in terms of registration costs. In cellular networks, a centralized top management level such as a mobile switching center (MSC), while conventional Mobile IP is distributed at the leaf nodes such as a home agent (HA) and a foreign agent. This results in a substantial increase in registration costs.
Conventional Mobile IP systems differ from cellular systems in other ways. For example, a home network size in conventional Mobile IP is much smaller than that in cellular networks. Therefore, if the same mobility rate is assumed to exist for conventional Mobile IP and cellular networks, the transition probability from a home network to a foreign network in Mobile IP is higher than that in cellular networks. This may be more clearly understood as follows.
FIG. 1 is a diagram showing an architecture of a conventional system for tracking a location of a mobile IP terminal. The system includes a home network 1 in which a home agent (e.g., server) of the mobile IP terminal is located, and a plurality of foreign networks 2 each having a foreign agent (FA) for managing communications with mobile nodes (MNs) in an associated coverage area.
In this system, when a mobile node moves away from its home network into foreign network FA2, the mobile node registers its location at its foreign agent and then the foreign agent sends information along signal paths to register the location of the mobile node at the home agent of the mobile node. The same is true when the mobile node moves between foreign agents such as from foreign networks FA1 to FA3, or from FA3 to FA4. As a result of this scheme, registration costs in the foreign network may be twice as costly as those in the home network. Moreover, registration costs in Mobile IP increases greatly if the foreign and home agents are distant from each other.
Conventional mobile IP and cellular networks are also different in the way they exchange messages. In conventional mobile IP, a mobile node receives data from a corresponding node via its foreign agent through its home agent when the mobile node moves away from the home network, while the mobile node sends data directly to the corresponding node. Thus, message exchanges are performed asymmetrically on conventional Mobile IP. Yet, in cellular networks, message exchanges are performed symmetrically in that the route to send and receive messages is the same.
In view of the foregoing comparison, it is clear that the efficiency and costs of conventional mobile IP systems have proven to be inferior to those of cellular networks. A need therefore exists for an improved system and method for managing the location and/or movement of IP terminals, and more specifically one which is more efficient to implement in terms of cost and management structure compared with conventional mobile IP systems, and which achieves a performance level approaching or equal to cellular networks when considered in an analogous context.